Wireless communications networks continue to provide access to an increasing number of resources and services. In many cases, a resource or service may demand a minimum quality of service (QoS) in order to deliver a desirable user experience. For example, real-time multimedia applications such as audio streaming, video streaming, and voice over internet protocol (VoIP) communications may demand a relatively high QoS in order to avoid delays in the delivery of content, which may be highly disruptive to an end user. Generally, radio resources in a wireless communications network are allocated via the establishment of one or more radio access bearers (RABs) between a radio access node and a wireless communications device. Each RAB is assigned certain QoS parameters, which are used by a scheduler in the radio access node to ensure that a minimum QoS is delivered for traffic over the RAB.
In an LTE network, one or more evolved RABs (E-RABs) may be established in what is known as an attach procedure, as illustrated in the call flow diagram shown in FIG. 1. First, an attach request is sent from user equipment (UE) 10 to an evolved node B (eNB) 12 (step 100). The attach request is forwarded from the eNB 12 to a mobility management entity (MME) 14 (step 102). The UE 10 is then authenticated by the MME 14 (step 104), which may involve one or more external nodes such as a home subscriber server (not shown). Next, a create session request is sent from the MME 14 to a selected serving gateway (S-GW) 16, indicating the address of a packet data network (PDN) gateway (P-GW) 18 with which a connection is desired and one or more desired QoS parameters for the E-RAB that will serve the connection (step 106). The S-GW 16 then forwards the create session request to the indicated P-GW 18 (step 108). In response to the create session request, the P-GW 18 performs an IP connectivity access network (IP-CAN) establishment procedure (step 110). As part of the IP-CAN establishment procedure, the requested QoS parameters are provided from the P-GW 18 to a policy charging and rules function (PCRF) 20 (step 112). The PCRF 20 may then optionally modify the QoS parameters as indicated by one or more preconfigured settings based on the requested resource and/or service, and send back one or more updated QoS parameters to the P-GW 18 (step 114).
A create session response is then sent from the P-GW 18 to the S-GW 16, which contains the QoS information for the requested resource or service and an IP address for the UE 10 (step 116). The create session response is forwarded from the S-GW 16 to the MME 14 (step 118). If the QoS parameters for the create session response indicate that a guaranteed bitrate (GBR) E-RAB is to be established, the MME 14 together with the eNB 12 may then perform admission control to determine if the necessary resources are present to establish a bearer with the required QoS. If the necessary resources are available, and/or if the QoS parameters for the bearer indicate that a non-GBR bearer is to be established, an attach accept message is sent from the MME 14 to the eNB 12 and the S-GW 16 at which point the eNB 12 may perform admission control based on the QoS required for the requested bearers (step 120). The attach message is forwarded from the eNB 12 to the UE 10 (step 122). In response to the attach message, the UE 10 sends and acknowledgement message (step 124), at which point in time an E-RAB is established between the UE 10 and the P-GW 18. Additional messages may then be exchanged between one or more network nodes in the LTE network order to complete the attach process.
The QoS parameters for the E-RAB are generally indicated by a QoS class identifier (QCI), which may define a resource type (GBR or non-GBR), a priority, a packet delay budget (PDB), a packet error loss rate (PELR), a guaranteed uplink/downlink bitrate, and a maximum uplink/downlink bitrate for the E-RAB. Generally, a QCI represents a preconfigured QoS for a wide range of resources and/or services that may be accessed via a particular E-RAB. Based on one or more of the QoS parameters in a QCI for a particular E-RAB, radio resources in a wireless communications network are scheduled. One common scheduling strategy known as delay-based scheduling involves increasing the priority of a packet as the time the packet has spent in a scheduling queue starts to approach the specified PDB for traffic on the E-RAB. While effective in some applications, a delay-based scheduling strategy based on the QoS parameters discussed above is not well suited to transfers of data content that must be finished before a certain transfer deadline. Further, such a delay-based scheduling strategy is generally over-aggressive, often scheduling radio resources unnecessarily and therefore overburdening a wireless communications network.
Accordingly, there is a present need for a scheduling strategy capable of ensuring that one or more transfers of data content can complete before a transfer deadline, while simultaneously increasing the efficiency of radio resource allocation in a wireless communications network.